Tool-maker&#39;s clamp.



c. HERTLE. TOOL MAKERS CLAMP.

APPLICATION FILED MAR. 7. 1918.

1 28E314, Patented Dec. 3, 1918.

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enemies Hearts, on Asmara, new YORK.

TOOL-IVIAKERS CLAMP.

for drilling purposes or other operations thereon.

Clamps of this type are usually constructed of two parallel jaws connected together by parallel screws so that by holding the heads of the screws one with each hand and swinging the jaws around one of the screws as on an axis, the jaws will close or open.

With the hitherto used construction of such clamps there is the drawback that one of the jaws which is not engaged by the threads of the screws has the tendency, during the closing and opening of the clamp, to drop or slide, which renders the clamp temporarily inoperative.

The object of my invention is to obviate this drawback by providing a construction in which the said jaw will always be held in a stationary position.

Another object of my invention is to so construct the device that themeans for the purpose set forth will be concealed within the jaw and thereby prevented from disarrangement or damage, rendering the clamp durable and inexpensive.

With these objects in view, my invention consists in the construction, combination and arrangement of parts as will be hereinafter more fully described and set forth in the appended claims. t

In the accompanying drawing similar reference characters denote corresponding parts and Figure 1 1s an elevation of the clamp; Fig. 2 an enlarged section on line 9r2 of Fig. 1; Fig. 3 a cross section on line.

33 of Fig. 2; Fig. 4 a cross section on line 4.-4: of Fig. 2 and Fig. 5 is a similar section as Fig. 2 showing the stationary jaw as being partly in engagement with the screw before these parts are permanently locked.

In the drawing a, 6 denote the jaws of the clamp of the usual shape and c, d the two parallel screws having heads 0, (2 respectively on the outer sides of the jaws. The

Specification of Letters Patent.

Application filed March 7, 1918. Serial No. 220396.

jaw o is provided with two parallel threaded I it bores a, a in which work respectively the screws 0, (Z. Thejaw b has in its inner or clamping surface a socket or groove 6 in which freely 0r rotatively bears the reduced end: 0 of the screw on ltalso has near its a other end a cylindrical bore 6 which in diameter is, about equal toor slightly larger than that of the threadedportion' of the screw d so that thelatter will freelypass therethrough and its unthreaded part 03 will rotatively bear within said bore. Now in order to prevent the jaw b from dropping 0r slipping down the screw cl during the swinging of the jaws for their adjustment into the proper clamping position, I provide the following construction:

The screw 03 is provided on its unthreaded portion d with an annular groove 6Z3. In the bore of the jaw, a groove 5 is provided which extends longitudinally from the outer open end thereof to an intermediate point which coincides with the lower edge of the annular groove @23 of the screw when the latter is in normal position. i This groove 6 is of uniform semicircular cross section throughout its length excepting at its lower end beginningfrom the upper edge of the annular groove (Z where it is enlarged by milling a groove 6 whose depth opposite the annular grooved is a small fraction of an inch larger than that of the bore 79 The excess depth is smaller than the depth of the annular groove d A ball 6, which in diameter is equal to the total depth of the bore 6 and the annular groove d serves to lock the screw al and the jaw 6 together. This locking will take place upon theentry of the ball 6 into the enlarged part of the groove 6 With the ball e located in the annular groove 01 of the screw cl, the latter can be passed through the bore 6 the projecting part of the ball fitting in the groove 6 When the ball arrives opposite the enlarged part I) of the groove, it will receive play which will permit it to become displaced relative to the groove (Z and bore 6 and lock the screw within the jaw. The upper or lower edge of the annular groove (i will, on the attempt to separate the parts, exert a lateral pressure on the ball and thrust the latter sidewise so that the escape of the ball through the groove 6 will not be possible.

Although a very simple means, yetthis look has proved to be very effective and to considerably improve the construction of this type of clamps.

What I claim and desire to secure by Letters Patent is:

1. A ball controlled joint consisting of one member having a bore formed with a longitudinal groove extending from its open end to an intermediate point of said member and enlarged at said point, and another member having an annular groove adapted when the members are in normal engagement to coincide with said enlarged portion of said longitudinal groove, and a ball engaging said annular groove and adapted when so engaged to snugly fit in said longitudinal groove and on its entry into the widened portion of the latter to permanently lock the two members together.

2. A clamp comprising parallel jaws and Copies of this patent may be obtained for ball engaging said annular groove and adapted when so engaged to snugly fit in said longitudinal groove and on its entry into the widened portion of the latter to permanently lock said screw to said jaw.

In testimony whereof I affix my signature in presence of two witnesses.

CHARLES HERTLE.

Witnesses:

FRED. J. GRIESMER, ELSIE SCHMID.

five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

